Wag Message Management; Figure 1-1. General Network Overview - Siemens A53457 Installation & Maintenance

DESCRIPTION

Figure 1-1. General Network Overview

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WAG MESSAGE MANAGEMENT

Upon startup of a WAG, it has an empty routing table. As devices report and respond, the WAG
dynamically updates the routing table.
When an Advanced Train Control System (ATCS) message comes into the WAG from the Ethernet,
Echelon, or a serial port, the WAG checks its internal routing table to see if it has seen the address
before. If the address is new, the WAG adds the source ATCS address of the message to its
internal routing table. If the ATCS device is already in the routing table, the WAG updates the
expiration timer in its routing table for that device.
After the routing table is updated, the WAG looks at the destination ATCS address of the message.
If the destination ATCS address appears in the routing table, the message is sent to the destination
device through the Ethernet, Echelon, or the serial port where the destination device can be
reached. If the destination ATCS device is not known, the ATCS message is sent to the specified
Broadcast Medium. During configuration, the user can specify the Broadcast Medium as Ethernet,
Echelon, or serial port. For more information about configuring, see Section 2.
If an ATCS device is turned off or otherwise stops communicating, the WAG times out the routing
table entry for the device and removes it from the routing table.
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Document No.: COM-00-05-16 June 2006, Revised June 2014
Version: C.1